One of my favorite astronomy anecdotes is that Pluto was predicted based on the gravity perturbation of Uranus and Neptune but when Clyde Tombaugh found it, it wasn't where it was supposed to be and pretty soon was determined to not have enough mass to be the "Planet X" everyone was looking for. Then over the decades they recalculated the orbits of Neptune and Uranus with greater and greater precision until at some point in the '60s, Carl Sagan(?) observed that at the current rate of diminishment, Pluto would cease to exist some time in the late '80s.
Of course, it's now impossible to find that quote because the whole world is all HURR DURR I LEARNED PLUTO HAZ PLANET SO WILL MY KIDZ without recognizing that the thing about science is it changes. I wonder if francopoli knows what I'm talking about.